I don't know whether or not they're all the same. The jaw-drive mechanism for my 'Alien' Hallowe'en costume was the 6-way pack from a '65 Mustang. It's essentially 3 motors in one case, with cable drives off of both ends of all 3 rotors. For my purposes, I removed 2 of the rotors, which still left it weighing at least a kilo. (That left me truckin' around with about 15 kg of steel on my head, but I had it suspended on springs from a welding helmet harness, so it was painless.
)
The pack itself was about 50% larger than a package of Smokies. (Maybe twice as big as a pack of wieners.)